Hydraulic pump or motor



, lune 13, 1939. l K, EN 2,161,794

HYDRAULIC PUMP OR MOTOR Filed Sept. 20, 1935 3 Sheets-Sheet 5 ELEK KJEIENEDEK Patented June 13, 1939 UNlTE-D STATES PATENT oFricE Elek K. Benedek; Bucyrns, Ohio Application September 20', 1935, Serial No. 41,475 V 6 Claims.

This invention relates to hydraulic pumps or motors, and ,more particularly to hydraulic pumps or motors of the type including a plurality of radially disposed piston and cylinder assemblies.

Machines of the kind referred to, in general comprise a stationary pintle provided with fluid transfer passages or conduits, a cylinder barrel rotatable about the pintle and being formed with a plurality of radially disposed, circumferentially spaced cylinders adapted to have valved communication with the pintle conduits, pistons in the cylinders, and means for effecting reciprocation of the pistons relatively to the respective cylinlli ders when the cylinder barrel is rotated. Be-

cause of their substantially continuous, positive pressure discharge characteristics, such pumps lately have found wide application in various fields, use for driving machine tools and hydraulic presses being representative examples of useful applications. Pumps of the general character referred to are well known and most of those heretofore available have been found satisfactory for many uses. They have, however, left something to be desired where required to discharge against high pressure, many prior pumps having shown a tendency to vibrate under such conditions, resulting in noise and premature mechanical failure. 1 I have found that such difiiculties are attributable in large measure to improper design and construction of the parts by which reciprocatory movements are imparted to the pistons and one object of my present invention is to provide improvements in the construction and organization of parts employed for this purpose whereby improved operation of the pump as a whole under high load conditions is obtainable.

Another object is to provide an improved load 4 transmitting ring and piston cross head assembly.

Another object is to provide an improved construction of piston cross head capable of general application in pumps of the character referred to above and more especially adapted for use in radial pumps in which the driving torque is transmitted directly from the cylinder barrel to the pistons, or vice versa.

A further objectis to provide a ring assembly or secondary rotor in thrust-transmitting relation to piston cross heads and comprising parts so constructed and assembled as to avoid the pinching or clamping of relatively movable parts such as the cross heads and cooperating thrust blocks. Further objects will become apparent from a reading of the following description, the appended claims, and the accompanying drawings, in

which:

Figure 1 is a section taken on the line .l-l of Figure, 2; ,5

Figure 2 is a section taken on the line 2-2 of Figure 1, a pump casing being shown' in addition tothe parts shown in Figure 1; I

Figure 3 is a view in elevation of a piston and cross head showing one form of cross head in ac- 10 cordance with the invention; a

. Figure 4 is a section taken on the line 4-4 of Figure 3;

Figure 5 is a view similar to Figure 3 but showing a different form of cross head; 15

Figure 6 is a view in elevation of an inner guide block;

Figure 7 is a top plan view of the guide block shown in Figure 6; 1

Figure 8 is a view showing a ring from which 20 guide blocks, such as shown in Figures 6 and 7, are made; I

Figure 9 is a section taken on the line 9-9 of Figure 8;

Figure 10 is a section through a guide block set 25 up in a jig for machining purposes taken onthe line Ill-l0 of Figure 11;

Figure 11 is a side view of the jig shown in Figure 10 with a plurality of guide blocks set up for machining;

Figure 12 is a fragmentary sectional view showing a modified form of cross head and cross head guiding means; a

Figure 13 is a section taken on the line I 3-43 of Figure 12, and

Figure 14 is a side view of an outer guide block.

The accompanying drawings show embodi- 'ments of the invention described hereinafter as being used for pumps, but it will be understood that the forms shown and described represent 40 only examples of various possible embodiments- In the form of pump shown for the purposes of illustration, there is provided a casing I comprising a combined end plate and flange part 2.

and anend plate 3 secured to the part 2 by 45 means of studs 4. A stationary. pin-tie 5 has a press fit in a bore 6 formed in the casing part I, the pintle being formed with a tapered part I flanked by cylindrical bearing surfaces 8 and 9 cooperating respectively with sets of roller bear- '50 ing elements l0 and II for mounting a cylindrical barrel I! for rotation about the pintle. The

cylindrical barrel is formed with a tapered bore I; which fits closely over thetapered portion 1 v of the pintle without having substantial bearing 55 contact therewith. Preferably, the cylinder barrel is provided with a chamber ll at the end of the pintle for holding a supply of lubricant for the bearings I l.

'The left-hand end of the barrel is formed with formed in the casing part I, and ball bearings l9.

The right-hand end of the cylinder barrel is formed with an annular seat 23 which receives the inner race 2| of an anti-friction bearing assembly including also an outer race 22 positioned in a seat 23 formed in the casing part 2 and ball bearings 24. An internally threaded ring member 2l has threaded connection with the righthand end portion of the cylinder barrel for maintaining the race member 2| in its seat. The cylinder barrel is adapted to be driven by any appropriate prime mover through the medium of a shaft 25.

The cylinder barrel-is formed with a plurality of radially disposed, circumferentiallyspaced cylinders 25 respectively communicating with ports 21 in turn adapted to have valved communication with cut-outs or ports 29 in the pintle, the

- ports 29 in turn having constant communication with bored passages 29 in the pintle. A piston 30 is mountedfor reciprocation in each'cylinder 23. When the cylinder barrel and pistons are rotated, the pistons will be reciprocated relatively to the associated cylinders in a manner to be described later, and the intake and discharge of fluid through the passages 29, the ports 29 and 21 into the cylinders 25 and thence outwardly through the passages 29 will take place in a manher well. understood in this art.

Improved means for reciprocating the.pistons include, in accordance with the present invention an outer non-rotatable ring 3| having an inner bearing face 32 forming a race for a plurality of small anti-friction bearing elements 33, anda rotary inner ring assembly 33 comprising two companion parts 35, 35 U-shaped in cross-section so as to provide an inwardly directed outer working surface 35 and outwardly directed working' surfaces 31. The ring parts 35, 35 are assembled in aligned relation by means of dowel pins 39,

Driving force is transmitted from the rin'gjl and ring assembly 33' tothe pistons through the.

and correspond in curvature to the outer working surface 36 of the ring assembly 35, theblocks 39 being also formed with flat surfaces engaging the outer faces of the respectively associated cross heads. The inner guide blocks 33 are provided with arcuate inner and outer surfaces cor- 7 responding respectively in curvature withthe curvature of the outer working surfaces 39 and the inner working'surfaces 31 of the ring assembly 35, 35. The guide blocks 49 are formed also with flat surfaces 33" engaging the inner faces of the cross heads 3|.

The guide blocks 39 and 33 fit snugly between the working surfaces 35 and 31 of the ring assembly 34, but a very slight circumferential clearance is provided between each guiderblock 39 and. the adjacent guide block 43 so as to permit slight relative circumferential movement between these parts during ,assembly, thereby enabling the cross head guiding and force-transmitting blocks to align themselves with respect to the cross heads and each other and thereby to prevent any binding action which otherwise might occur due to even very slight inaccuracy in machining of the parts. After the cross heads, the

'blocks 39 and ,and the ring parts 35, 35 have been assembled, bolts 32 arepassed through the ring parts 35, 35 and through holes provided therefor in the inner guide blocks 40, and the parts 353549 then clamped in rigid assembly. From the foregoing it will be apparent that althoughthe outer (thrust) guide blocks 39 each has only one arcuate surface engaging the rings 35, 35, each of the inner guide blocks 33 is formed with two arcuate surfaces fitting snugly between the outer and inner working surfaces 39 and 31 of the ring assembly 35, thereby providing a very rigid assembly and eliminating to a large extent vibrations which would occur if the legs of the U-shaped ring parts 35, 35 were left unsupported and permitted to flex.

It is important in order to obtain an assembly of maximum rigidity that the outer and inner arcuate surfaces of the guide blocks 43 fit very closely between the outer and inner working surfaces 35 and 31 of the ring assembly 35, 35. In

, order to obtain such a fit, I preferably make the blocks 49 as indicated in Figures- 8 to 11, inclusive. The first step in manufacture is indicated in Figure 8 which represents a complete ring which is turned and ground to provide an outer surface corresponding in curvature to the outer working surface 35 of the ring assembly 35, 35, and an inner surface corresponding in curvature to that ofthe inner working surface 31 of the ringassembly. After the ring, shown in Figure 8, has been turned and ground to these dimensions, observing a close tolerance, it is formed with equl-distantly spaced bores for receiving the bolts 42. The ring is then cut into a plurality of sectors which are placed in a jig such as shown in Figrues 10 and 11, and then machined to provide the surfaceslll', shown in Figure 10, for engagement with thepiston cross heads.

In Figures 1 and 2, the parts are shown in neutralposition, i. e., with the pistons and cross heads and ring assembly 35, 35 disposed concentrically with respect to the cylinder barrel and pintle. It will be understood that .when the parts are in this concentric position, rotation ofthe cylinder barrel will not effect reciprocation of the pistons. In order to effect reciprocation of the-pistons, it is necessary to shift the ring assembly 35, 35 and associated parts to a position eccentric with respect to the cylinder barrel and pintle. To this end, the outer ring member 3| may be provided with pads l5, 35 adapted to slide upon pads (not shown) in the pump casing, and with rods 33, 33 for effecting the shifting movement ,of the ring 3|.

The cross heads may beintegral .with or separatefrom and connected to the pistons 39, but

' preferably, whichever arrangement is employed.

the pistons should be reduced in cross section adjacent the cross heads 4|,as shown at 55. This provides a limited amount of flexibility: preventing the creation of abnormal str which otherwise might result from shocks caused by transmission of driving torque from the cylinderbarrel to the cross heads and associated rotatable rings.

In accordance with ya further. feature of the present invention, the cross heads themselves are so constructed as to provide'for flexibility each of said assemblies; and cross head guiding provided with slots 41 extending inwardly from its ends toward, but not all the way to. thecen- .tral portion 48 which, of course, is solid.. In the form shown in Figures 3 and 4 the cross heads are drilled, as at 49, and slots 50 then cut in-- wardly from the end of the cross head to the drilled holes 49, the slots being cut in such a manner that theydecrease inwidth from their open ends-inwardly. In this form also the slots terminate short of the slit central portion 5|. With this slotted construction, the cross heads will deflect slightly under the stresses caused by torque transmission so that the bearing surfaces of the cross heads will be inclined slightly with respect to the cooperating surfaces of the blocks 39 and 40, thereby providing for the formation of a high pressure. wedge-shaped oil film between the cross head working faces and the associated blocks. The arrangement is such that the solid central portions of the cross heads transmit the radially imposed thrust upon the pistons, whereas the slotted end portions serve to transmit the torque for rotating the ring assembly 35, 35. Thus, it will be seen that the major function of transmitting high thrust loads to the pistons'is performed by solid parts of the cross heads, whereas transmission of torque for rotating the ring assembly 35, is performed by means of the slotted and. therefore, relatively flexible end portions; operating in such manner as to create and maintain an effective wedgeshaped oil film bearing.

In a modified construction illustrated in Figures 12 and 13, the ring assembly differs from that disclosed in-Figures 1 and 2 in that there is no surface corresponding tothe inner working surface, 31 shown in Figures 1 and 2. In the Figure 12 and Figure 13 construction, ring parts 35 ,35 have inwardly directed flanges providing outer working surfaces 35 adapted to engage the outer curved surface of the outer bearing blocks 39". The ring parts 35 35 are formed with bores 52 serving as races for roller bearings 53 which mount cylindrical bearing elements 54, each;

formed with-a central bore 55 through which'is adapted to pass a clamping device or bolt 56 having a head '51 and receiving a nut 58 by. means of which the ring parts 35 35*- are clamped in assembled relation. The cross head 59, shown in Figure 12, has its outer face in engagement with the blocks 39 and its inner face in engagement with cylindrical bearing elements 54, there being two such elements for each cross head as shown.

The bores 55 of the cylindrical elements 54 are large enough to provide ample clearance between the cylindrical elements and the bolts 55 so that the cylindrical elements maybe rotated in their roller bearing mountings ,without' engaging the bolts. T

The embodiments of the invention shown and described herein for the purpose of illustration are the present preferred forms oi. the invention,

but it willbe understood that changes may be made in the specific construction and relative arrangement of the parts without departingfrom the invention as defined in the claims. r I claim: V f 1. ma hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including a piston element :and'

a cylinder element, the combination of cross heads connected respectively to one element of means having thrust-transmitting surfaces engageable respectively with said cross heads and being located radially outwardly beyond and directly in the line of the axis of the associated piston and cylinder assembly, each cross head comprising a member at least one end portion of which is bifurca ted'towards but not all the way a cylinder element, the combination of cross heads connected respectively to one element of each. of said assemblies; and cross head guiding means having thrust-transmitting surfaces engageable respectively with said crossheads and being .located radially outwardly beyond and directly in the line of the axis of the associated piston and cylinder assembly, each cross head comprising a member the opposite ends of which are bifurcated inwardly towards but not all the way to the middle, and said crosshead comprising a solid portion disposed between the element of said piston and cylinder assembly to which the crosshead is connected and the associated thrust-transmitting surface.

-3. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including-a piston element and a cylinder element, the combination of cross heads connected respectively to one element of each of said assemblies; and cross head guiding means line with the axis of the associated piston andv cylinder'assembly, whereby there is provided a non flexible thrust transmitting connection directly in the line of thrust. V L

4. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including afpiston element and a cylinder element, thecombination. of cross heads connected respectivel'y to one element of each of said assemblies; andcross head guiding means engageable with said cross heads, each cross head comprising. a plate-like member solid adjacent its point of connection to said element and being formed with slots, extending inwardly from its ends in a plane normal to the center line of the associated piston and cylinder assembly, said slots decreasing .inyridth from the open ends inwardly.

5. In a hydraulic pump ormotorof the type assemblies, each including a piston element and a cylinder element, the combination of a rotary ring member'ha'ving an annular working surface; a cross head connected to one element of each of said assemblies; and and force-transmitting means for each cross head comprising an outer guide block connected'to' said ring memher and engaging the outer .faceeof said cross formed to correspond in curvature with the curvature oi the annular working surface of said ring member and engaging the latter surface, said inner guide block means comprising a plurality of circumferentially spaced blocks, each being interposed between two adjacent cross heads. and. their respectively associated outer guide blocks.

6. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including a piston element anda cylinder element, the combination of a rotary ring member having radially spaced inwardly directed and outwardly directed annular working surfaces; a cross head connected to one element of each of said assemblies; and guiding and forcetransmittlng means for each cross head comprising an outer guide block formed with an arcuate head, and inner guide block means arcuately.

outer surface having a curvature corresponding to that of. the inwardly directed annular working surface of said ring member and engagingisaid latter surface, the inner surface of said guide block engaging the outer face of said cross head, and inner guide block means comprising .a plurality of circumferentially spaced inner blocks, each being interposed between two adjacent cross heads and their respectively associated outer guide blocks, each ofsaid inner block's being'formed with inner and outer arcuate surfaces having curvatures corresponding respectively to the curvatures of the inner and outer working surfaces of said ring member and engaging said later sur- 

